An LCD panel is a main part of a typical LCD. When an LCD panel is manufactured, a common process is to manufacture a set of LCD panels joined together in a single LCD panel board. The LCD panel board is then cut up into a plurality of individual LCD panels. In detail, this process typically includes the following steps: forming electrodes on a pair of substrates; coating two alignment films on the substrates respectively, and rubbing the alignment films; distributing spacers on the substrates; coating a sealant on one of the substrates; adhering the two substrates together; cutting the substrates into a plurality of LCD panel preforms (or cells); injecting liquid crystal into each of the cells; and sealing each of the cells, thereby obtaining the plurality of LCD panels.
FIG. 15 is a side view of a conventional LCD panel. The LCD panel 100 includes two LCD substrates 110, two alignment films 160 respectively coated on inner surfaces of the LCD substrates 110, a liquid crystal layer 150 interposed between the alignment films 160, a sealant 130, and a plurality of spacers 140. The sealant 130 is used to support and adhere the LCD substrates 110 together. The LCD substrates 110 and the sealant 130 cooperatively form an accommodating space. The spacers 140 are located in the accommodating space, and liquid crystal molecules of the liquid crystal layer 150 are received in the accommodating space. The spacers 140 are also used to support the LCD substrates 110, so as to maintain a certain constant gap therebetween.
Referring also to FIG. 16, one of the LCD substrates 110 of the LCD panel 100 is shown. The LCD substrate 110 defines a display region 112, a periphery region 114, and a sealant adhering region 115 between the display region 112 and the periphery region 114. The sealant adhering region 115 corresponds to the sealant 130. During the process of coating the alignment film 160 on the substrate 110, polyimide liquids (one of the materials of the alignment film 160) are only printed on the display region 112 and the periphery region 114. Thereby, the alignment film 160 is formed only on the display region 112 and the periphery region 114, without covering the sealant adhering region 115.
FIG. 17 is a schematic view illustrating a process of rubbing the alignment film 160 on one of the LCD substrates 110. The LCD substrate 110 is mounted on a workbench 12 of a rubbing device (not labeled). A rubbing cloth 11 is wrapped on a roller 10 of the rubbing device. The workbench 12 is moved horizontally toward the roller 10, and the roller 10 rotates in a predetermined direction to cause the rubbing cloth 11 to rotate correspondingly. Thus the rubbing cloth 11 directly contacts the alignment film 160 and steadily rubs the alignment film 160 from one side of the LCD substrate 110 to an opposite side of the LCD substrate 110.
After rubbing the alignment film 160, a great deal of loose particles of polyimide are liable to remain on the whole LCD substrate 110. The particles on the display region 112 and the periphery region 114 may be removed easily. However, the particles in the sealant adhering region 115 are difficult to remove, because the sealant adhering region 115 is lower than the display region 112 and the periphery region 114. If the particles in the sealant adhering region 115 are not removed, an area of contact between the sealant 130 and the substrate 110 is reduced. This means the bonding strength of the sealant 130 with the substrate 110 is correspondingly reduced.
What is needed, therefore, is an LCD substrate that can overcome the above-described deficiencies.